The present invention relates in general to current controlling and more particularly concerns novel apparatus and techniques for controlling output current while keeping harmonics low with a rugged reliable circuit that is self-protecting against short circuit and open circuit.
It is an important object of the invention to provide methods and means for controlling an a-c load current with an a-c voltage independently of the load.
It is another object of the invention to achieve one or more of the preceding objects while providing protection against the output terminals to which the load is connected being short circuited and open circuited.
It is a further object of the invention to achieve one or more of the preceding objects while adjusting load current by varying an input voltage.
It is a further object of the invention to achieve one or more of the preceding objects while producing a sine wave load current in the presence of a highly distorted voltage in the circuit.
It is a further object of the invention to achieve one or more of the preceding objects to produce a sine wave load current even when driving loads with highly nonlinear characteristics.
It is still another object of the invention to achieve one or more of the preceding objects with components that are relatively low in cost and highly reliable.
It is still a further object of the invention to achieve one or more of the preceding objects with high efficiency.
It is still another object of the invention to achieve one or more of the preceding objects with a system in which the desired load current rapidly follows a desired change designated by a change in control voltage.